Disney star Cameron Boyce, who died last week in his sleep following a seizure, suffered from epilepsy, his family confirmed on Wednesday.

The 20-year-old actor, best known for his starring role in the Descendants TV movies, passed away "due to a seizure as a result of an ongoing medical condition, and that condition was epilepsy," the family told People magazine.

"We are still trying to navigate our way through this extremely heart-wrenching time, and continue to ask for privacy so that the family and all who knew and loved him can grieve his loss and make arrangements for his funeral - which in and of itself, is agonizing," his family added.

The Los Angeles County Medical Examiner's office said on Monday that an autopsy had been performed on Boyce, but an official cause of death has yet to be announced.

The medical examiner said the actor was found unresponsive at his home on Saturday afternoon and was pronounced dead at the scene.

Tributes have poured in for the actor since his death, including from former first lady Michelle Obama, who tweeted a photo with Boyce on Tuesday night.

"I was lucky enough to share a few moments with Cameron Boyce - on set, at the White House and on a service project - enough time to recognize that not only did he have incredible talent, but also an incredible heart," Obama wrote in the post. 

"Sending love & hugs to his family, friends and his many, many fans."

The actor's Descendants co-star Dove Cameron also posted a tearful six-part video on Instagram, referring to Boyce as an "earth angel."

"Cameron was one of my favorite people alive in the world, though I know that's not unique to me," the actress posted. 

"Cameron was magic - an earth angel.

"Over the last six years, since he was only 14, Cameron talked me down from countless ledges, talked me through eating disorders, helped me out of a dark relationship and through endless breakdowns," she said, adding that the actor was "the ultimate example of a human being."